Recently, there has been increasing interest in comparing educational leadership measures, such as principal school leadership, using International Large-Scale Assessments (ILSAs) data. However, when considering the socio-cultural, economic, and linguistic diversity across countries participating in ILSAs, there are doubts about the uniformity of the measurement tools regarding their robustness levels and psychometric characteristics. The current study examines the uniformity of cross-cultural model-data for principal school leadership scale using the framework and data supplied by the OECD's (TALIS) 2018. Multiple-group confirmatory factor analysis (MGCFA) is employed to estimate the conceptual measurement model and test measurement invariance across forty-eight countries and later, dividing countries into more homogenous groups. The results of this study revealed that the scale measuring principals' school leadership was found to be invariant across all countries only at an intermediate level (i.e. metric) which means the factor structures and the factor loadings are equivalent across the countries, the item intercepts of principal school leadership scale are not. However, when testing within sub-groups, it is observed that there are improvements in cross-cultural comparability. This paper concludes by suggesting information on promoting scale improvement and discusses the implications of this study for policymaking and recommendations for future research.